The Sm complex is required for the processing of non-coding RNAs by the exosome

Area of Science:

• Molecular Biology
• RNA Biology
• Gene Regulation

Background:

• The exosome complex plays a critical role in RNA degradation and processing.
• Certain non-coding RNAs, including spliceosomal small nuclear RNAs (snRNAs) and telomerase RNA, evade degradation and become functional molecules.
• A common feature of these stable RNAs is the presence of the Sm complex at their 3' end.

Purpose of the Study:

• To investigate the role of the Sm binding site in the exosome-mediated processing of telomerase RNA.
• To determine if the Sm binding site influences the maturation of snRNAs.
• To explore the exosome's role in telomerase RNA biogenesis and its conservation across species.

Main Methods:

• Genetic analysis in Saccharomyces cerevisiae and Schizosaccharomyces pombe.
• RNA processing assays to monitor telomerase RNA and snRNA maturation.
• Introduction of Sm binding sites into unstable RNA molecules to assess stabilization.

Main Results:

• An intact Sm binding site is essential for the exosome-mediated processing of telomerase RNA into its mature, functional form in yeast.
• The same pathway involving the Sm binding site and exosome is critical for snRNA maturation.
• Introducing an Sm binding site into an exosome-targeted RNA confers partial stability.
• Telomerase RNA accumulates in Schizosaccharomyces pombe exosome mutants, indicating a conserved regulatory role.

Conclusions:

• The Sm binding site is a key determinant for the processing and stabilization of specific non-coding RNAs by the exosome.
• This mechanism of RNA processing and biogenesis is conserved between yeast species.
• The findings provide mechanistic insights into how the exosome regulates RNA processing and telomerase RNA biogenesis.